Schemes to avoid periodic resource collisions

ABSTRACT

Systems, methods and circuitries are provided for performing UE autonomous selection in a vehicle-to-anything (V2X) communication environment, that includes one or more processors configured to schedule resources for discontinuous periodic transmission having a scheduled discontinuous time period in which scheduled resources are not transmitted. The one or more processors are further configured to perform a monitoring operation at the scheduled discontinuous time period, the monitoring operation comprising a monitoring for a collision of scheduled resources of the evaluating UE with scheduled resources of a competing UE, and selectively perform a corrective action when a collision of scheduled resources of the evaluating UE with scheduled resources of the competing UE is detected during the monitoring operation.

BACKGROUND

The 3GPP standard body released the C-V2X standard to support V2X (i.e.,vehicle-to-everything) communication. NR V2X includes two modes ofoperation, identified as Mode 1 and Mode 2. Mode 1 deals with gNB (e.g.,base station) scheduling, while Mode 2 deals with autonomous selection.M ode 2 does not require the support of cellular infrastructure, andvehicles can autonomously select their sub-channels for their V2Vtransmissions.

BRIEF DESCRIPTION OF THE DRAWINGS

Some examples of circuits, apparatuses and/or methods will be describedin the following by way of example only. In this context, reference willbe made to the accompanying figures.

FIG. 1 is a time-frequency diagram illustrating the two step sensing andselection for V2X autonomous selection.

FIG. 2 is a diagram illustrating a potential collision problem in V2Xautonomous selection for periodic transmission schemes.

FIG. 3A is diagram illustrating a discontinuous periodic transmissionscheme to address the collision problem with a periodic transmissionscheme with a V2X autonomous selection process according to an aspect.

FIG. 3B is a flow diagram illustrating the discontinuous periodictransmission scheme of FIG. 3A according to an aspect.

FIG. 4 is a diagram illustrating a unique collision condition with V2Xautonomous selection when a competing UE has an resource reservationperiod (RRP) that is an integer multiple of an evaluating UE accordingto an aspect.

FIG. 5 is a diagram illustrating a unique collision condition with V2Xautonomous selection when an evaluating UE has an RRP that is an integermultiple of a competing UE according to an aspect.

FIG. 6 is a flow diagram illustrating differing corrective actionsdepending upon the relative RRPs of the evaluating UE and a competing UEin a V2X autonomous selection process using a discontinuous periodictransmission scheme according to an aspect.

FIGS. 7A-7B are diagrams illustrating discontinuous periodictransmission schemes in instances where multiple, non-contiguousresource blocks are scheduled in each transmission period according tovarious aspects.

FIGS. 8A-8B are diagrams illustrating discontinuous periodictransmission schemes in instances where multiple, non-contiguousresource blocks are scheduled in each transmission period according tovarious aspects.

FIG. 9 is a diagram that illustrates the signaling performed to “skip” atransmission period to effectuate the discontinuous periodictransmission.

FIG. 10 is a flow diagram illustrating functions of one or moreprocessors of an evaluating UE performing a self-collision detectionscheme using HARQ feedback information.

FIG. 11 is a block diagram illustrating a UE and various componentsthereof according to an aspect.

DETAILED DESCRIPTION

The present disclosure is described with reference to the attachedfigures. The figures are not drawn to scale and they are provided merelyto illustrate the disclosure. Several aspects of the disclosure aredescribed below with reference to example applications for illustration.Numerous specific details, relationships, and methods are set forth toprovide an understanding of the disclosure. The present disclosure isnot limited by the illustrated ordering of acts or events, as some actsmay occur in different orders and/or concurrently with other acts orevents. Furthermore, not all illustrated acts or events are required toimplement a methodology in accordance with the selected presentdisclosure.

As highlighted above, Mode 1 in NR V2X involves vehicle directcommunication with one another, however, those communications aremanaged by a cellular infrastructure that selects the sub-channels andtime slots or radio resources for each V2V transmission. In contrast,Mode 2 in NR V2X does not require the support of the cellularinfrastructure, and vehicles autonomously select the sub-channels andtime slots or radio resources for their V2V transmissions. In thisframework, the 3GPP standard defines a distributed semi-persistentscheduling scheme that all the vehicles must implement.

C-V2X supports 10 MHz and 20 MHz channels. The channel is dividedtemporally into 1 ms sub-frames and into resource blocks (RBs) of 180KHz each. The standard defines a sub-channel as a group of RBs in thesame sub-frame. The sub-channels are used to transmit data and controlinformation. Such data is transmitted in transport blocks (TBs) overphysical sidelink shared channels (PSSCH), and the control informationis transmitted in sidelink control information (SCI) messages overphysical sidelink control channels (PSCCH). A TB contains a full packetand can occupy one or several sub-channels. Each TB has an SCIassociated therewith, and both are transmitted in the same sub-frame.The SCI occupies a configurable number of RBs and configurable number ofOFDM symbols and includes information such as the modulation and codingscheme (MCS) used to transmit the TB, and the RBs that the TB occupies,and the resource reservation period (RRP) for the semi-persistentscheduling scheme. The resource reservation period refers to theperiodicity used by vehicles to transmit their packet, and the period orinterval is specified in multiples of 100 ms (e.g., 100 ms, 200 ms, . .. 1000 ms). The information on the SCI is valuable, so the SCI must becorrectly received to receive and decode the TB.

In Mode 2, vehicles autonomously select their sub-channels and timeslots using a sensing based semi-persistent scheduling (SPS) scheme,wherein vehicles reserve the selected sub-channels and time slots for anumber of consecutive packet transmissions, dictated by a reselectioncounter value. After such number of transmissions, new resources orsub-channels must be selected and reserved. The process by which avehicle selects and reserves resources is a multi-step process, whichcan be appreciated with reference to FIG. 1 . Note that FIG. 1technically illustrates an LTE two-step procedure, but for purposes ofunderstanding the substance, it is sufficient for explanatory purposes.At a high level, in a sensing step (or sensing window shown in FIG. 1 )the UE listens to the channel, i.e., listening for channel information(SCI of other vehicles) in order to see what resources are alreadyreserved. In a selection step candidate resources are identified andsubsequently selected or reserved.

More particularly, whenever a new resource is to be selected, resourcescan be reserved by the vehicle in a time period called the selectionwindow, as shown in FIG. 1 . Within this time period the vehicleidentifies the candidate single sub-frame resources (CSRs) to bereserved. A CSR is a group of adjacent sub-channels within the samesub-frame where the packet or SCI and TB resides. If “T” is thebeginning time of a time window in which the new resource selection mustbe made (i.e., the selection window), the vehicle senses all packets ina preceding sensing window that includes 1000 subframes before T. Thevehicle creates a list that includes all the CSRs in the sensing window(i.e., candidate CSRs), except for CSRs that satisfy two criteria: (1)the resource is indicated in a received SCI from another vehicle(indicating that another vehicle will utilize that resource at the sametime, and (2) a measured average reference signal received power (RSRP)over the RBs used to transmit the TB associated with the SCI of theother vehicle is greater than a RSRP threshold. If both conditions aremet, the vehicle excludes that particular CSR as a candidate CSR. Thevehicle then may perform a resource selection for a transmission fromthe identified candidate resources (CSRs) in the selection window.

As discussed above, in those instances when a periodic resourcereservation is made, when the vehicle UE initiates transmission on theselected resources, it does not monitor the sidelink channels due to thehalf-duplex system constraint, and consequently if another vehicle UEselects the same periodic resources for its own sidelink transmissions,such dueling sideline transmissions could possibly continuously collidewith each other. This undesired collision condition is illustrated inFIG. 2 , wherein UE 1 and UE2 correspond to two different vehicles thatare transmitting on the same selected time-frequency resources (i.e.,the same sub-channel at the same time).

As shown in FIG. 2 , a first UE 202 (e.g., UE1 corresponding to a firstvehicle) has a first periodic resource reservation 204 at a time t₁,while a second UE 206 (e.g., UE2 corresponding to a second vehicle) hasa second periodic resource reservation 208 that occupies the sametime-frequency resources as the first reservation 204. Further, in theexample of FIG. 2 , both resource reservations 204, 208 have the sameperiodicity 210 and thus not only is there a collision at time t₁, butthe data collisions continue at times t₂, t₃, t₄. etc. In light of theappreciated issues highlighted above, the present disclosure providescircuitry, a methodology and a non-transitory computer readable mediumfor discontinuous periodic transmission that addresses this issue.

In one aspect, the UE (referred to as the evaluating UE) intentionallydoes not transmit in one of the scheduled, reserved time periods (whichmay be referred to as a scheduled discontinuous time period), andinstead performs a channel monitoring on the periodically reservedresources. If during the monitoring function, an SCI of another UE(referred to as a competing UE) is detected, some form of correctiveaction is selectively performed, wherein the form of corrective actionis based on the resource reservation period (RPP) and in some instanceson a data priority of the competing UE. For example, in one aspect inwhich data priority is not a factor or a consideration, the form ofcorrective action based on the RRP may depend upon whether RRPs of theevaluating UE and the competing UE are: (1) identical, (2) the competingUE's RRP is an integer multiple of the evaluating UE's RRP, or (3) theevaluating UE's RRP is an integer multiple of the competing UE's RRP.FIG. 3A-5 illustrate the three conditions highlighted above to helpunderstand how the corrective action may differ based on the relativeRRPs.

FIG. 3A illustrates condition (1) above, wherein the evaluating UE 302(e.g., UE1) and the competing UE 304 (e.g., UE2) have reserved the sametime-frequency resources (e.g., resources 306 and 308 are the same). Inaddition, in this example, the reserved resources 306, 308 have the sameperiodicity 310, meaning that the RRPs of the resources 306, 308 areidentical. Therefore absent any corrective action, data collisions willoccur and not be detected by either UE 302, 304. In this example, UE 302is the evaluating UE and elects to not transmit at a time period (i.e.,t₃), and instead performs a monitoring operation 312 of the channel atthat time period. By not transmitting at the otherwise scheduled timeperiod (e.g., a scheduled discontinuous time period), the evaluating UE302 is performing a discontinuous periodic transmission. If, at themonitoring time period t₃ an SCI of a competing UE is detected anddecoded that indicates the same time-frequency resource having anidentical RRP, the evaluating UE 302 stops transmitting on the collidingresources, and instead initiates a re-selection procedure, wherein theUE 302 performs the two-part sensing and selection procedure discussedsupra with respect to FIG. 1 to schedule other resources. This is seenin FIG. 3A at 314, wherein the transmission at time t₄ is not performedand instead a re-selection procedure is initiated.

The above example discussion ignores the issue of data priority. Thatis, in the example of FIG. 3A, the evaluating UE 302 discontinuestransmission at t₄ independently of whether or not the priority of thedata transmission of the evaluating UE 302 is higher or lower than thatof the competing UE 304. In one aspect, the evaluating UE 302 performsthe monitoring operation 312 at t₃ and decodes an SCI indicating acolliding transmission with a competing UE having an identical RRP. Theevaluating UE 302 then further evaluates the data transmission priorityof the competing UE 304, for example, by evaluating the decoded SCI ofthe competing UE 304, and if the data transmission priority of theevaluating UE 302 is higher than the priority of the competing UE 304data transmission, then the evaluating UE 302 does not discontinuetransmission. In this case, despite the collision, because of the higherdata priority, the evaluating UE 302 does not stop transmitting, butinstead continues to transmit.

In one aspect, if each of the UEs are operating in accordance with thepresent disclosure, the competing UE 304 is sometimes operating as anevaluating UE and in such instance would detect the collision and higherdata priority of the other competing UE, and in response woulddiscontinue transmission and initiate a re-selection procedure.

Therefore as highlighted above in conjunction with FIG. 3A, thedisclosure contemplates a UE, or one or more processors in a UE that,upon executing instructions are configured to perform discontinuousperiodic communication 350 with another UE, as set forth in FIG. 3B. Theprocess 350 may be the functions of an apparatus comprising thefunctions of one or more processors in an evaluating UE, may be amethod, and/or may be non-transitory computer readable media containinginstructions that when executed by one or more processor result in thefunctions described herein. At 352, the one or more evaluating UEprocessors are configured to schedule resources for discontinuousperiodic transmission. As highlighted above, such scheduling lookssimilar to that of UE1 302 that schedules a monitoring operation at ascheduled discontinuous time period (e.g., t₃ of FIG. 3A) that wouldotherwise be used for a data transmission. Such scheduling includesreservation of periodic time-frequency resources. Further details ofsuch scheduling will be discussed infra. Such scheduling details are setforth in the SCI and may include the periodicity, data priority, as wellas other parameters that characterize the discontinuous periodiccommunication.

Still referring to FIG. 3B, the one or more UE processors perform themonitoring operation according to one of various methods. In one optionthe monitoring operation is scheduled according to a random selectionwith a probability (A) that may be preconfigured or may be a function ofother criteria, such as data priority. In another aspect the selectionof the monitoring process timing may follow a predefined pattern, suchthat the nature of the discontinuous transmission itself has aperiodicity. Further details of how and when such monitoring is executedwill be discussed in further detail infra.

During the monitoring operation at 354, the one or more UE processorsmonitor the channel for the SCI of other transmitting UEs (i.e.,competing UEs) at 356. If no other transmissions are detected, or if anSCI is detected, but upon decoding does not include reserved resourcesthat would collide with the evaluating UE (NO at 356), the discontinuousperiodic transmission is continued at 358 until the next scheduledmonitoring event. If, however, an SCI of a competing UE is detected thatdoes conflict with the reserved resources of the evaluating UE (YES at356), the one or more UE processors (i.e., the evaluating UE) performs acorrective action at 360.

In one aspect, the corrective action taken at 360 comprisesdiscontinuing the periodic transmission by the evaluating UE, and theninitiating a re-selection process, where the UE does the two stepsensing and selection procedure discussed above in conjunction with FIG.1 . In another aspect, the corrective action can be selective, whereinthe discontinuation of data transmission is contingent upon the relativedata priority levels or some other criteria. For example, upon decodingthe SCI of the competing UE, if the scheduled resources conflict, butthe relative data priorities of the evaluating UE and the competing UEmeet some predetermined relationship, the evaluating UE will notdiscontinue transmission despite the detection of the collisions. Forexample, if the data priority of the evaluating UE is greater than thatof the competing UE, the transmission may continue. Alternative, othercriteria may be employed to make the corrective action at 360 selective.

As discussed above, the type of corrective action taken by an evaluatingUE may differ based on the RRP of the evaluating UE and the competingUE. Option (2) corresponds to the condition where the RRP of thecompeting UE is an integer multiple of the evaluating UE (e.g., if theperiod of the evaluating UE is 100 ms, the period of the competing UE is100 ms X “N”, wherein N is an integer), and is illustrated in FIG. 4 .As shown in FIG. 4 , a competing UE 404 performs periodic transmissionthat exhibits a period that is an integer multiple of the periodtransmission of the evaluating UE 402. In this example, the integer is2, and thus the evaluating UE 402 transmits data twice as often as thecompeting UE 404. As can be seen in FIG. 4 , in such a situation, acollision will not occur for every evaluating UE transmission, but willoccur for every competing UE transmission. In this example, a collisionoccurs at t₁, but not at t₂. When the evaluating UE 402 discontinuestransmission and instead performs a monitoring operation 410 at t₃, theevaluating UE 402 decodes the SCI of the competing UE 404 and sees thatit has an RRP that is an integer multiple of the evaluating UE RRP(e.g., 100 ms compared to 200 ms). At this point, the evaluating UE mayselect a few different options for its corrective action. In one aspectthe evaluating UE discontinues only those transmissions at collidingtime periods (e.g., 412 and 414), while continuing to transmit at theother, non-conflicting time periods. In this case, the evaluating UE 402does not initiate a re-selection procedure, but instead just skipstransmitting on the colliding resources. Alternatively, the evaluatingUE 402 may elect to initiate a re-selection procedure. In yet anotheralternative aspect, upon identifying the condition, the evaluating UE402 may employ other criteria in deciding whether to skip collidingresource time periods 412, 414 or initiate re-selection. For example ifthe data transmission priority for the evaluating UE 402 is “high”(e.g., above a predetermined threshold), re-selection might beinitiated. Alternatively re-selection could be initiated if the priorityis “low” according to some predetermined criteria or threshold. Anyother substantive criteria could be employed and is appreciated to becontemplated by the present disclosure.

As highlighted above, if condition (3) exists, and the evaluating UEsRRP is an integer multiple of the competing UE's RRP, the situationlooks like FIG. 5 . As shown in FIG. 5 , an evaluating UE 502 and acompeting UE 504 both are performing periodic transmission and thescheduling of such will result in collisions due to occupying some ofthe same time-frequency resources. In this instance, the evaluating UE502 will experience a collision at each and every transmission, whilesome fraction of transmissions of the competing UE 504 will experience acollision (based on the integer multiple of the RRP). When theevaluating UE 502 performs a monitoring operation 508 at t₃ instead of adata transmission and discovers the issue via the competing UE's SCI,the evaluating UE 502 may elect to discontinue transmission and insteadinitiate a re-selection process. Alternatively, upon detecting thecondition the UE may choose to message the competing UE 504 with arequest that the competing UE 504 skip the colliding resources in thecertain periods where the collision would exist. In yet anotheralternative, the evaluating UE 502 may take into account its datapriority and/or the data priority of the competing UE 504 in decidingwhich corrective action to take under such circumstances. For example ifthe data transmission priority of the competing UE is “high”, instead ofrequesting the competing UE 504 to skip transmissions in the collidingtime periods, the evaluating UE 502 may elect to discontinuetransmission and initiate a re-selection procedure.

In summary, the variations in corrective action based on the threediffering relationships between the evaluating UE's RRP and thecompeting UE's RRP is set forth in FIG. 6 . FIG. 6 shows the functionsperformed by an evaluating UE's one or more processors. As shown in FIG.3 , when an affirmative answer is made at 356 to the query of whether anSCI is detected in the evaluating UE's reserved resources (YES at 356),a corrective action 360 is performed. FIG. 6 provides greater detailregarding what the corrective action may entail depending on therelationship of the RRPs between the evaluating UE and the competing UE.

Initially, the one or more processors of the evaluating UE compares itsRRP with that of the competing UE via its decoded SCI. If the RRPs arethe same (YES at 662), each transmission of each UE will collide, asillustrated in FIG. 3A. In one aspect the evaluating UE checks to see ifits data priority is lower than the data priority of the competing UE at664. If not (NO at 664), then the evaluating UE may elect to take nofurther corrective action at 666. This might reflect a situation wherethe evaluating UE has much higher priority data than the competing UE,and if the competing UE is also performing discontinuous periodictransmission, it will detect the collision, stop transmission andperform re-selection. If the determination is made that the datapriority of the evaluating UE is lower than that of the competing UE(YES at 664), the evaluating UE stops transmitting and performs are-selection procedure at 668. Note that the analysis at 664 regardingthe data priority is optional (as represented by the dashed lines) andalternatively if the conclusion at 662 is affirmative (YES), theevaluating UE may proceed straight to 668, discontinue transmission, andperform re-selection.

Still referring to FIG. 6 , if the RRPs of the evaluating UE and thecompeting UE are not identical (NO at 662), a determination is madewhether the RRP of the competing UE is an integer multiple of theevaluating UE at 670. If it is (YES at 670), the situation illustratedin FIG. 4 exists, and the evaluating UE queries whether its datapriority is higher than the data priority of the competing UE at 672. Ifthe evaluating UE data priority is greater (YES at 672) no correctiveaction is taken at 674. That is, while there are clearly data collisionsat 412 and 414, as shown in FIG. 4 , because that evaluating UE's datapriority is sufficiently high according to some predetermined standard,the evaluating UE may continue to transmit. If the competing UE is alsoperforming discontinuous periodic transmission, it may detect thecondition, and since it has a lower data priority, it may stoptransmission and perform a re-selection. If the query at 672 is negative(NO at 672), the evaluating UE may elect one of two different options.In one case, the evaluating UE may stop transmitting solely with respectto the colliding resources at 676, as illustrated in FIG. 4 , whereresources 412 and 414 are cancelled, but transmission continues for theother evaluating UE resources. In another aspect, if the evaluating UEdata priority is not “high” according to some predefined criteria, theevaluating UE discontinues all data transmission and initiates are-selection process at 678. Again, the data priority analysis at 672may be optional, as shown by the dashed lines

Still referring to FIG. 6 , if the result of the query at 670 isnegative (NO at 670), then another query is made whether the RRP of theevaluating UE is an integer multiple of the competing UE at 680. If so(YES at 680), the situation is as illustrated in FIG. 5 . Under theseconditions the evaluating UE has two available options, wherein at 682the evaluating UE stops transmission and performs a re-selection, or theevaluating UE sends a message to the competing UE to skip thosetransmissions associated with the colliding resources at 684. Ifhowever, the query at 680 is answered in the negative (NO at 680), thena situation exists where RRPs of the evaluating UE and the competing UEare mutually prime. For example, this situation would exist if the RRPof the evaluating UE was 30 ms and the RRP of the competing UE was 100ms. In another alternative, if the RRP of the competing UE is 0, whichmeans the competing UE only uses the resources once, and is notperforming periodic transmissions. In such case, no corrective action istaken at 674.

In the examples provided in FIGS. 3-5 , only a single set or block ofresources are scheduled within each transmission period. In analternative aspect, multiple, non-contiguous sets or blocks of resourcesmay be scheduled for periodic transmission by a UE. This example isillustrated in FIG. 7A, where a first UE1 702 and a second UE2 704 areperforming periodic transmission, wherein within each transmissionperiod multiple, non-contiguous sets or blocks of time-frequencyresources are scheduled for transmission. For example, the first UE1 702has a first resource block 706 and a second resource block 708, whilethe second UE2 has a first resource block 710 and a second resourceblock 712 scheduled within each transmission period. As illustrated inFIG. 7A, according to the scheduling, the first resource blocks 706, 710of the UEs 702, 704 do not collide, but the second resource blocks 708,712 do collide.

In one aspect, during a third time period 714, the first UE1 702 doesnot transmit, but instead performs a monitoring operation 716 where itlistens to the channel for the SCI of other competing UEs. In this case,UE1 702 detects the SCI of UE2 704, decodes it, and determines that thesecond resource blocks 708, 712 collide, and thus a corrective actionmust take place. In one aspect, as illustrated in FIG. 7A, the first UE1702 (i.e., the evaluating UE) stops all further transmissions on all thereserved resources, which in this case corresponds to both resourceblocks 706, 708, and performs a re-selection procedure. In analternative aspect, as illustrated in FIG. 7B, in a similar situationwherein only a portion of the scheduled resources collide (i.e.,resource blocks 708, 712 collide, but resource blocks 706, 710 do notcollide), the evaluating UE 702 discontinues transmissions only on thecollided resources in the subsequent transmission periods, andoptionally performs a re-selection procedure solely for the collidingresources.

In the examples of FIGS. 7A-7B, the evaluating UE 702 performed itsmonitoring operation for each resource block 706, 708 within the sametransmission period 714. Alternatively, an evaluating UE may scheduleand thus perform a monitoring operation for each of the resource blocksin different transmission periods. For example as illustrated in FIG.8A, a first UE1 802 transmits in each transmission period according toscheduled resource blocks 806, 808, while a second UE2 804 transmits ineach transmission period according to scheduled resource blocks 810,812. As shown in FIG. 8A, the first resource blocks 806, 810 of the UEs802, 804 do not collide, while the second resource blocks 808, 812 ofthe UEs 802, 804 do experience a collision. In contrast to FIG. 7A wherethe evaluating UE 702 performs a monitoring operation for both blocks706, 708 in the same transmission period 714, in the aspect of FIG. 8A,the evaluating UE 802 monitors 815 for the first block 806 in a secondtransmission period 814, and monitors 817 for the second block 808 in athird transmission period 816. As illustrated, the evaluating UE 802does not detect a conflicting resource with respect to block 806 in thesecond transmission period 814, but does detect a collision with respectto the block 808 in the third transmission period 816. In one aspect, asillustrated in FIG. 8A, the corrective action taken by the evaluating UE802 is to discontinue transmission of all resources and perform are-selection procedure for all the resources.

In an alternative aspect illustrated in FIG. 8B, a similar collisioncondition is detected, that is, a partial collision is detected. Moreparticularly, a collision is detected for some (i.e., resource 808), butnot all the resources (i.e., resources 806 and 808). In this aspect, thecorrective action taken by the evaluating UE 802 is to discontinuetransmission of only the colliding resource (i.e., resource 808) whilecontinuing transmission of the other non-colliding resources, as shownin FIG. 8B. In yet another alternative, the corrective action may beconditioned upon other criteria. For example, a priority of the dataassociated with the reserved resource block may be considered. If thepriority of the data associated with the colliding resource block is“high” (e.g., it exceeds a predetermined threshold), the collidingresource is re-scheduled, and if it is not a “high” priority, theevaluating UE 802 simply discontinues transmission on that collidingresource, and maintains transmission on the non-colliding resource.

In one aspect, this discontinuous periodic transmission schemehighlighted herein may be selectively enabled or disabled, and inanother aspect it may be a fixed solution or may be configured orpreconfigured per resource pool. Either alternative is contemplated bythe present disclosure.

As discussed above, the problem associated with collisions in periodictransmission is addressed by an evaluating UE discontinuing its periodictransmission and performing a monitoring operation during the timeperiod it would otherwise be transmitting in order to determine whethera competing UE exists that has reserved resources that will conflictwith those of the evaluating UE in a manner discussed herein andillustrated in FIGS. 3A, 4-5, 7A-7B and 8A-8B. One or more ways in whichthe monitoring function is scheduled to form a discontinuous periodictransmission is described below.

In one aspect of the present disclosure, prior to each transmission onresources in a given period, the UE determines whether or not totransmit on the next transmission period, and if a determination is madeto transmit, the UE populates its SCI field accordingly. In one aspect,the determination whether or not to transmit (or monitor) on the nexttransmission period is made based on a random selection of whether tomonitor in the next period, wherein the random selection has aprobability (A) that may be configured or preconfigured, or based oncriteria such as data priority. For example, if the probability (A) isconfigured or preconfigured to be 10%, then the chance that theevaluating UE will choose to not transmit, but instead monitor duringthe next transmission period will be 10%.

In accordance with an alternative aspect, the probability (A) may dependon various criteria, for example, in one aspect the probability (A) maydepend upon the data priority. For example, in one aspect, theprobability (A) may be increased for high priority data to ensurereliable data transmissions, and decreased for low priority data.Alternatively, the probability (A) may be decreased for high prioritydata to achieve more continuous data transmissions, and increased forlow priority data to avoid collisions with higher priority data incompeting UEs.

In accordance with another alternative aspect, the probability (A) maydepend upon collision history. If a relatively high number of collisionwere detected (according to some predetermined threshold or criteria) ina recent predefined time period, the probability (A) may be increased tomonitor more frequently, and if the recent history showed no orinfrequent collisions, the probability (A) may be decreased. In otheraspects, multiple factors or criteria may be collectively considered informing or otherwise configuring the probability (A).

In addition, for non-contiguous multiple resources reserved in eachtransmission period, such as that illustrated in FIG. 8A, theprobability may be independently applied to each of the variousscheduled resources in the time period.

In another aspect, the monitoring of the evaluating UE may follow apredetermined pattern or periodicity. For example, in one aspect, theperiodic transmissions are discontinuous due to monitoring every “B”time periods. The value B may be (pre)configured or may be randomlyselected from a set of preconfigured periods. For example, the set maybe mutually prime number such as {2, 3, 5, 7, 11} which may avoidconsecutive identical discontinuous resources from different UEs. Inanother aspect, the selection of the value B may depend upon datapriority. For example, the value B may be selected to be a lower valuefor high priority data to monitor more often to ensure more reliabletransmission, and B made larger for lower priority data. In anotheraspect, B may be higher for high priority data to ensure more continuoustransmission for such data. In addition, in one aspect, once theperiodicity B is selected, the starting point needs to be determined aswell. In one aspect, the starting period of the discontinuous resourcetime period may be randomly selected between 0 and B−1. Alternatively,the starting point can be configured or preconfigured, or based on othercriteria.

The above discussion discloses determining how often to make theotherwise periodic transmission discontinuous by scheduling themonitoring operation. The manner in which such discontinuoustransmission is signaled can be performed in a variety of differentways. In one aspect, if the evaluating UE determines a discontinuoustransmission in the next time period, the evaluating UE alters the RRP(i.e., the resource reservation period) field of the SCI to skip thenext transmission time period. In one aspect, if the present RRP is setto 100 ms, the evaluating UE sets the RRP in the SCI that is associatedwith PSSCH one period before the discontinuous transmission to 200 ms(double the periodicity). In another example, if the RRP is set to 400ms, the RRP for the SCI one period before the discontinuous transmissionis set to 800 ms to double the periodicity and effectively “skip” thatparticular transmission period so it can be utilized to monitor thechannel. One example of this feature is illustrated in FIG. 9 , whereinthe SCI field indicates one period for the normal periodic transmission,and then indicates “2× period” on the period prior to the monitoringoperation 914, to indicate that the transmission on the scheduledresources skips to the “next” transmission period after thediscontinuous (monitoring) time period.

In another aspect, an additional bit may be employed in the SCI field toindicate a discontinuous transmission in the next transmission period.For example, if the extra bit is set to “0”, for example, the resourcein the next transmission period is reserved and periodic transmissioncontinues. If the extra bit is set to “1”, for example, the resource inthe next transmission period is not reserved and monitoring may beperformed, and the resource will be reserved for transmission in theperiod following the monitoring period.

In various aspects discussed above, a discontinuous periodictransmission scheme is disclosed, wherein an evaluating UE stopstransmitting during a discontinuous time period to monitor the channelfor potential collisions. In another aspect, periodic transmission isnot discontinued, but instead a transmitting UE operates as anevaluating UE and performs a self-detection of collision operation byevaluating the feedback from one or more receiving UEs when HARQfeedback is enabled. Alternatively, the transmitting UE operates as anevaluating UE by looking for HARQ feedback on sideline feedback channel(PSFCH) resources that correspond to PSCCH and PSSCH transmissions byother transmitting UEs to inferentially ascertain collisions when HARQfeedback is disabled.

In one aspect, self-detection of a collision may be performed by atransmitting UE performing a periodic transmission. For example, in asidelink unicast or groupcast transmission with HARQ feedback enabled,the transmitting UE can evaluate the received feedback over a number ofevaluated feedback messages, and calculate what percentage of suchmessages are negative acknowledgements (NACKs). If the percentage ofsuch NACKs exceeds a predetermined threshold, then it is determined thata collision exists with a competing UE with respect to the scheduledresources.

As is known, a unicast transmission is a one-to-one communication,wherein a transmitting UE is transmitting the periodic transmission to asingle, specific receiving UE. In response to the unicast transmission,the transmitting UE receives a response to the sidelink data packet fromthe receiving UE when HARQ feedback is enabled. In general, a HARQ-ACKis a response that indicates whether a sidelink data packet wassuccessfully received. Available HARQ-ACK responses include, inter alia,positive acknowledgement (ACK), negative acknowledgement (NACK), andDTX. As only an ACK indicates a successful receipt of the transmitteddata, either a NACK or a DTX is deemed to be a “NACK” for purposes ofthis disclosure, and thus represent an unsuccessful transmission thatmay be due to a collision. Thus, in a periodic transmission, forsuccessive transmissions of the data, receipt of NACK or DTX is countedas a “fail” while an ACK is treated as a “success.” If the percentage of“fails” is larger than a threshold, then the transmitting UE concludesthat a collision exists with respect to the scheduled periodicresources. In such instances a corrective action is performed, forexample, where the periodic transmission is discontinued and are-selection procedure is initiated.

In one aspect the threshold used to conclude a collision has occurred ispreconfigured or configured. In another aspect, the threshold may bebased on a data quality-of-service (QoS) parameter or a data prioritylevel. For example, if the QoS or data priority is high, the thresholdmay be lower to trigger a re-selection operation if there is only aremote possibility that a collision exists.

Referring to FIG. 10 , a UE for self-detecting collisions 1000 in aperiodic communication environment employing, for example, autonomousselection is provided. Such a UE is a transmitting UE that also operatesas an evaluating UE to detect collisions with competing UEs. FIG. 10also may correspond to a method of performing self-detection ofcollisions in the above environment using or more processors, andfurther may entail non-transitory computer readable media containinginstructions that when executed by one or more processors performs themethod described herein.

In one aspect, the functionality 1000 begins at 1002, wherein a query ismade whether HARQ feedback is enabled in the UE. As the standard allowsfor HARQ feedback to be selectively enabled, the functionality 1000provides for two different options. If HARQ feedback is enabled (YES at1002), then the transmitting UE will receive ACK/NACK type feedback inresponse to the periodic transmissions.

Upon knowledge of HARQ feedback being enabled, the transmitting UEreceives resources for periodic communication and schedules suchresources with one or more feedback-based collision detection parametersat 1004. Non-limiting examples of such feedback-based collisiondetection parameters may be as follows. One parameter may be a number oftotal transmissions 1006 in the periodic transmission. For example, ifthe transmitting UE is associated with a vehicle, it may be transmittinga vehicle velocity periodically a total number of 100 times, or 500times, before it needs to reschedule. This information may also includea period to dictate how frequently such data is to be transmitted.Another feedback collision detection parameter may be a number of datacollection transmissions 1008 for collecting NACK statistics. In oneexample, if the total number of periodic transmissions is 100, thenumber of transmissions to be used or evaluated for collecting NACKstatistics may be 10. Thus the UE will evaluate the first 10 HARQfeedbacks with respect to the 100 transmissions and make its decisionbased on the 10 pieces of HARQ feedback data.

Still referring to FIG. 10 , another feedback collision detectionparameter may include a data collection format 1010. For example, in theexample already provided, the analysis of potential collision may bebased on 10/100 transmissions. In one data format 1010 only the first 10pieces of HARQ feedback data are considered. In another aspect, eachsubsequent set of 10 pieces of HARQ feedback information are evaluatedthroughout the entire transmission, such that transmissions 1-10 areevaluated, then 11-20, then 21-30, and so on. In another aspect, thedata collection format may be a sliding window, where pieces of HARQfeedback information 1-10 are evaluated, then 5-15 are evaluated, then10-20, then 15-25, and so on. The data collection format 1010 allowsflexibility in customizing a manner in which the self-collision dataanalysis will be conducted.

Another feedback collision detection parameter is a threshold 1012. Forexample, as NACK statistics are collected, the percentage of receivedNACKs can be compared to the threshold, and if the NACK percentageexceeds the threshold, a conclusion is made that a collision exists onthe scheduled resources. For example, if 10 of the 100 transmissions areevaluated with respect to their HARQ feedback responses, and 2 of the 10HARQ feedback responses were NACKs, then the NACK percentage is 20%. Ifthe threshold 1012 is 30% a conclusion is made that no collision exists,whereas if the threshold is 10% a conclusion is made that a collisionhas occurred with a competing UE on the reserved resources.

Referring back to FIG. 10 , once the reserved resources are scheduledwith the feedback-based collision detection parameters at 1004, aperiodic transmission is initiated and takes place at 1014 by thetransmitting UE. As the periodic transmission is taking place at 1014,NACK statistics are collected at the transmitting UE at 1016 via theHARQ feedback, and such NACK statistics are collected according to oneor more of the feedback-based collision detection parameters. Theprocess 1000 continues to 1018, wherein the NACK statistics areconverted to a percentage, for example, and compared to the threshold1012. If the threshold is not exceeded (NO at 1018), a conclusion may bemade that no collision presently exists with respect to the reservedresources, and if the periodic transmission is still continuing (NO at1020), additional NACK statistics may be collected depending on the datacollection format 1010. If periodic transmission has completed (YES at1020), then no corrective action is needed, as no resource collision hasbeen detected.

Referring back to act 1018 of FIG. 10 , if the computed NACK percentagedoes exceed the threshold (YES at 1018), then a conclusion is made thata collision has occurred and a corrective action is selectivelyperformed at 1024. In one aspect, the corrective action is todiscontinue the periodic transmission and initiate a re-selectionprocess. In one aspect, the corrective action may be selective based onvarious other criteria.

Returning to query 1002 in FIG. 10 , if the HARQ feedback is not enabled(NO at 1002), then the transmitting UE will not be receiving HARQfeedback information. However, if other competing UEs are transmittingand employing HARQ feedback, then such information may be detected bythe evaluating UE on a feedback channel, such as the physical sidelinkfeedback channel (PSFCH) at 1030. If during a monitoring the PSFCH, HARQfeedback is detected (YES at 1032), then an inference can be made thatthe periodic transmission made by the evaluating UE is colliding with atransmission of a competing UE, and a corrective action is performed at1024. In one example, the corrective action is discontinuing theperiodic transmission and initiating a re-selection process. If no HARQfeedback is detected on PSFCH, for example (NO at 1032), then aconclusion is made that no collision exists, and no corrective action istaken at 1034. For example, the periodic transmission of the evaluatingUE continues.

In the descriptions above, description is made in conjunction withseveral flow diagrams outlining example methods. In this description andin the appended claims, use of the term “determine” with reference tosome entity (e.g., parameter, variable, and so on) in describing amethod step or function is to be construed broadly. For example,“determine” is to be construed to encompass, for example, receiving andparsing a communication that encodes the entity or a value of an entity.“Determine” should be construed to encompass accessing and readingmemory (e.g., lookup table, register, device memory, remote memory, andso on) that stores the entity or value for the entity. “Determine”should be construed to encompass computing or deriving the entity orvalue of the entity based on other quantities or entities. “Determine”should be construed to encompass any manner of deducing or identifyingan entity or value of the entity.

As used herein, the term identify when used with reference to someentity or value of an entity is to be construed broadly as encompassingany manner of determining the entity or value of the entity. Forexample, the term identify is to be construed to encompass, for example,receiving and parsing a communication that encodes the entity or a valueof the entity. The term identify should be construed to encompassaccessing and reading memory (e.g., device queue, lookup table,register, device memory, remote memory, and so on) that stores theentity or value for the entity.

As used herein, the term select when used with reference to some entityor value of an entity is to be construed broadly as encompassing anymanner of determining the entity or value of the entity from amongst aplurality or range of possible choices. For example, the term select isto be construed to encompass accessing and reading memory (e.g., lookuptable, register, device memory, remote memory, and so on) that storesthe entities or values for the entity and returning one entity or entityvalue from amongst those stored. The term select is to be construed asapplying one or more constraints or rules to an input set of parametersto determine an appropriate entity or entity value. The term select isto be construed as broadly encompassing any manner of choosing an entitybased on one or more parameters or conditions.

As used herein, the term derive when used with reference to some entityor value of an entity is to be construed broadly. “Derive” should beconstrued to encompass accessing and reading memory (e.g., lookup table,register, device memory, remote memory, and so on) that stores someinitial value or foundational values and performing processing and/orlogical/mathematical operations on the value or values to generate thederived entity or value for the entity. “Derive” should be construed toencompass computing or calculating the entity or value of the entitybased on other quantities or entities. “Derive” should be construed toencompass any manner of deducing or identifying an entity or value ofthe entity.

As described herein, for purposes of discussion, each vehicle employingV2X communication principles are described as a UE (i.e., userequipment). FIG. 11 illustrates a non-limiting example of a platform1100 (or “device 1100”) in accordance with various aspects that mayconstitute circuitry that makes up a UE. In aspects, the computerplatform 1100 may be suitable for use as UEs and/or any otherelement/device discussed herein. The platform 1100 may include anycombinations of the components shown in the example. The components ofplatform 1100 may be implemented as integrated circuits (ICs), portionsthereof, discrete electronic devices, or other modules, logic, hardware,software, firmware, or a combination thereof adapted in the computerplatform 1100, or as components otherwise incorporated within a chassisof a larger system. The block diagram of FIG. 11 is intended to show ahigh level view of components of the computer platform 1100. However,some of the components shown may be omitted, additional components maybe present, and different arrangement of the components shown may occurin other implementations.

Application circuitry 1105 includes circuitry such as, but not limitedto one or more processors (or processor cores), cache memory, and one ormore of LDOs, interrupt controllers, serial interfaces such as SPI, I2Cor universal programmable serial interface module, RTC, timer-countersincluding interval and watchdog timers, general purpose I/O, memory cardcontrollers such as SD MMC or similar, USB interfaces, MIPI interfaces,and JTAG test access ports. The processors (or cores) of the applicationcircuitry 1105 may be coupled with or may include memory/storageelements and may be configured to execute instructions stored in thememory/storage to enable various applications or operating systems torun on the system 1100. In some implementations, the memory/storageelements may be on-chip memory circuitry, which may include any suitablevolatile and/or non-volatile memory, such as DRAM, SRAM, EPROM, EEPROM,Flash memory, solid-state memory, and/or any other type of memory devicetechnology, such as those discussed herein.

As examples, the processor(s) of application circuitry 1105 may includea general or special purpose processor, such as an A-series processor(e.g., the A13 Bionic), available from Apple® Inc., Cupertino, Calif. orany other such processor. The processors of the application circuitry905 may also be one or more of Advanced Micro Devices (AMD) Ryzen®processor(s) or Accelerated Processing Units (APUs); Core processor(s)from Intel® Inc., Snapdragon™ processor(s) from Qualcomm® Technologies,Inc., Texas Instruments, Inc.® Open Multimedia Applications Platform(OMAP)™ processor(s); a MIPS-based design from MIPS Technologies, Inc.such as MIPS Warrior M-class, Warrior I-class, and Warrior P-classprocessors; an ARM-based design licensed from ARM Holdings, Ltd., suchas the ARM Cortex-A, Cortex-R, and Cortex-M family of processors; or thelike. In some implementations, the application circuitry 1105 may be apart of a system on a chip (SoC) in which the application circuitry 1105and other components are formed into a single integrated circuit, or asingle package.

The baseband circuitry 1110 may be implemented, for example, as asolder-down substrate including one or more integrated circuits, asingle packaged integrated circuit soldered to a main circuit board or amulti-chip module containing two or more integrated circuits.

The platform 1100 may also include interface circuitry (not shown) thatis used to connect external devices with the platform 1100. The externaldevices connected to the platform 1100 via the interface circuitryinclude sensor circuitry 1121 and electro-mechanical components (EMCs)1122, as well as removable memory devices coupled to removable memorycircuitry 1123.

A battery 1130 may power the platform 1100, and may have a power supplycoupled to an electrical grid. The battery 1130 may be a lithium ionbattery, a metal-air battery, such as a zinc-air battery, analuminum-air battery, a lithium-air battery, and the like. In someimplementations, such as in V2X applications, the battery 1130 may be atypical lead-acid automotive battery.

While the methods are illustrated and described above as a series ofacts or events, it will be appreciated that the illustrated ordering ofsuch acts or events are not to be interpreted in a limiting sense. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein. In addition, not all illustrated acts may be required toimplement one or more aspects or examples of the disclosure herein.Also, one or more of the acts depicted herein may be carried out in oneor more separate acts and/or phases. In some examples, the methodsillustrated above may be implemented in a computer readable medium usinginstructions stored in a memory. Many other examples and variations arepossible within the scope of the claimed disclosure.

EXAMPLES

Example 1 is an evaluating user equipment (UE) that comprises a memoryand one or more processors communicatively coupled to the memory. Theone or more processors are configured to schedule resources fordiscontinuous periodic transmission having a scheduled discontinuoustime period in which scheduled resources are not transmitted, andperform a monitoring operation at the scheduled discontinuous timeperiod, the monitoring operation comprising a monitoring for a collisionof scheduled resources of the evaluating UE with scheduled resources ofa competing UE. The one or more processors are also configured toselectively perform a corrective action when a collision of scheduledresources of the evaluating UE with scheduled resources of the competingUE is detected during the monitoring operation.

Example 2 includes the subject matter of example 1, wherein whenscheduling resources for discontinuous periodic transmission, the one ormore processors are configured to determine whether the evaluating UEwill transmit on a next transmission time period based on a randomselection having a probability that the next transmission time period isa discontinuous time period and thus not scheduled for data transmissionon the next transmission time period.

Example 3 includes the subject matter of example 2, wherein theprobability is a preconfigured probability value.

Example 4 includes the subject matter of claim 2, wherein theprobability depends upon a data priority associated with the scheduledresources.

Example 5 includes the subject of example 4, wherein the probability isa high probability value greater than a nominal probability value if thedata priority is greater than a predefined threshold.

Example 6 includes the subject matter of example 1, wherein whenscheduling resources for discontinuous periodic transmission, the one ormore processors are configured to determine whether the evaluating UEwill transmit on a next transmission time period based on a predefinedperiodicity of the scheduled discontinuous time period in whichscheduled resources are not transmitted.

Example 7 includes the subject matter of example 6, wherein thepredefined periodicity is randomly selected from a set of preconfiguredperiods.

Example 8 includes the subject matter of example 6, wherein thepredefined periodicity depends upon a data priority associated with thescheduled resources.

Example 9 includes the subject matter of example 1, wherein whenscheduling resources for discontinuous periodic transmission, the one ormore processors are configured to determine that a next period will be adiscontinuous transmission period, and set a resource reservation period(RRP) field of a sidelink control information (SCI) message of theevaluating UE to a new value that doubles a period of periodictransmission with respect to a previous RRP field value of theevaluating UE.

Example 10 includes the subject matter of example 1, wherein whenscheduling resources for discontinuous periodic transmission, the one ormore processors are configured to determine that a next period will be adiscontinuous transmission period, and set a bit in a sidelink controlinformation (SCI) message field to a predetermined value that indicatesthat a scheduled resource in the next transmission period is notreserved for data transmission, but the scheduled resource in atransmission period following the next transmission period is reservedfor data transmission.

Example 11 includes the subject matter of example 1, wherein whenperforming the monitoring operation at the scheduled discontinuous timeperiod, the one or more processors are configured to evaluate one ormore relevant frequency channels for sidelink control information (SCI)messages of one or more competing UEs, and for each SCI message detectedin the relevant frequency channels, determine whether any scheduledresources of the one or more competing UEs collide with scheduledresources of the evaluating UE.

Example 12 includes the subject matter of example 1, wherein whenselectively performing the corrective action when a collision isdetected, the one or more processors are configured to evaluate whethera resource reservation period (RRP) of a competing UE is identical to anRRP of the evaluating RRP, and selectively stop discontinuous periodictransmission by the evaluating UE on the scheduled resources and performa re-selection operation to reschedule resources for discontinuousperiodic transmission on different reserved resources.

Example 13 includes the subject matter of example 12, wherein the one ormore processors are further configured to determine whether a datapriority of the evaluating UE is greater than a data priority of thecompeting UE, and take no corrective action if the data priority of theevaluating UE is greater than the data priority of the competing UE.

Example 14 includes the subject matter of example 1, wherein whenselectively performing the corrective action when a collision isdetected, the one or more processors are configured to evaluate whethera resource reservation period (RRP) of a competing UE is an integermultiple of the RRP of the evaluating UE, and selectively stop periodictransmission on only those reserved resources by the evaluating UE thatcollide with transmissions of the competing UE when the RRP of thecompeting UE is an integer multiple of the RRP of the evaluating UE.

Example 15 includes the subject matter of example 14, wherein the one ormore processors are configured to determine whether a data priority ofthe evaluating UE is greater than a data priority of the competing UE,and take no corrective action if the data priority of the evaluating UEis greater than the data priority of the competing UE.

Example 16 includes the subject matter of example 1, wherein whenselectively performing the corrective action when a collision isdetected, the one or more processors are configured to evaluate whethera resource reservation period (RRP) of the evaluating UE is an integermultiple of the RRP of the competing UE, and send a message from theevaluating UE to the competing UE to skip periodic transmission onscheduled resources that collide with the scheduled resources of theevaluating UE when the RRP of the evaluating UE is an integer multipleof the RRP of the competing UE.

Example 17 includes the subject matter of example 1, wherein whenselectively performing the corrective action when a collision isdetected, the one or more processors are configured to evaluate whethera resource reservation period (RRP) of the evaluating UE is an integermultiple of the RRP of the competing UE, and stop discontinuous periodictransmission and perform a re-selection operation to rescheduleresources for discontinuous periodic transmission on different reservedresources.

Example 18 is directed to a method of performing user equipment (UE)autonomous selection in an evaluating UE. The method comprisesscheduling resources for discontinuous periodic transmission having ascheduled discontinuous time period in which scheduled resources are nottransmitted using the one or more processors, and performing amonitoring operation at the scheduled discontinuous time period, themonitoring operation comprising a monitoring for a collision ofscheduled resources of the evaluating UE with scheduled resources of acompeting UE the one or more processors. The method also comprisesselectively performing a corrective action when a collision of scheduledresources of the evaluating UE with scheduled resources of the competingUE is detected during the monitoring operation using the one or moreprocessors.

Example 19 includes the subject matter of example 18, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises determining whether the evaluating UE will transmit on a nexttransmission time period based on a random selection having aprobability that the next transmission time period is a discontinuoustime period and thus not scheduled for data transmission on the nexttransmission time period.

Example 20 includes the subject matter of example 19, wherein theprobability is a preconfigured probability value.

Example 21 includes the subject matter of example 19, wherein theprobability depends upon a data priority associated with the scheduledresources.

Example 22 includes the subject matter of example 21, wherein theprobability is a high probability value greater than a nominalprobability value if the data priority is greater than predefinedthreshold.

Example 23 includes the subject matter of example 18, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises determining whether the evaluating UE will transmit on a nexttransmission time period based on a predefined periodicity of thescheduled discontinuous time period in which scheduled resources are nottransmitted.

Example 24 includes the subject matter of example 23, wherein thepredefined periodicity is randomly selected from a set of preconfiguredperiods.

Example 25 includes the subject matter of example 23, wherein thepredefined periodicity depends upon a data priority associated with thescheduled resources.

Example 26 includes the subject matter of example 18, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises determining that a next period will be a discontinuoustransmission period using the one or more processors, and setting aresource reservation period (RRP) field of a sidelink controlinformation (SCI) message of the evaluating UE to a new value thatdoubles a period of periodic transmission with respect to a previous RRPfield value of the evaluating UE using the one or more processors.

Example 27 includes the subject matter of example 18, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises determining that a next period will be a discontinuoustransmission period, and setting a bit in a sidelink control information(SCI) message field to a predetermined value that indicates that ascheduled resource in the next transmission period is not reserved fordata transmission, but the scheduled resource in a transmission periodfollowing the next transmission period is reserved for datatransmission.

Example 28 includes the subject matter of example 18, wherein whenperforming the monitoring operation at the scheduled discontinuous timeperiod, the method comprises evaluating one or more relevant frequencychannels for sidelink control information (SCI) messages of one or morecompeting UEs, and for each SCI message detected in the relevantfrequency channels, determining whether any scheduled resources of theone or more competing UEs collide with scheduled resources of theevaluating UE.

Example 29 includes the subject matter of example 18, wherein whenselectively performing the corrective action when a collision isdetected, the method comprises evaluating whether a resource reservationperiod (RRP) of a competing UE is identical to an RRP of the evaluatingRRP, and selectively stopping discontinuous periodic transmission by theevaluating UE on the scheduled resources and perform a re-selectionoperation to reschedule resources for discontinuous periodictransmission on different reserved resources.

Example 30 includes the subject matter of example 29, and furthercomprises determining whether a data priority of the evaluating UE isgreater than a data priority of the competing UE, and taking nocorrective action if the data priority of the evaluating UE is greaterthan the data priority of the competing UE.

Example 31 includes the subject matter of example 18, wherein whenselectively performing the corrective action when a collision isdetected, the method comprises evaluating whether a resource reservationperiod (RRP) of a competing UE is an integer multiple of the RRP of theevaluating UE, and selectively stopping periodic transmission on onlythose reserved resources by the evaluating UE that collide withtransmissions of the competing UE when the RRP of the competing UE is aninteger multiple of the RRP of the evaluating UE.

Example 32 includes the subject matter of example 31, and furthercomprises determining whether a data priority of the evaluating UE isgreater than a data priority of the competing UE, and taking nocorrective action if the data priority of the evaluating UE is greaterthan the data priority of the competing UE.

Example 33 includes the subject matter of example 18, wherein whenselectively performing the corrective action when a collision isdetected, the method further comprises evaluating whether a resourcereservation period (RRP) of the evaluating UE is an integer multiple ofthe RRP of the competing UE, and sending a message from the evaluatingUE to the competing UE to skip periodic transmission on scheduledresources that collide with the scheduled resources of the evaluating UEwhen the RRP of the evaluating UE is an integer multiple of the RRP ofthe competing UE.

Example 34 includes the subject matter of example 18, wherein whenselectively performing the corrective action when a collision isdetected, the method comprises evaluating whether a resource reservationperiod (RRP) of the evaluating UE is an integer multiple of the RRP ofthe competing UE, and stopping discontinuous periodic transmission andperform a re-selection operation to reschedule resources fordiscontinuous periodic transmission on different reserved resources.

Example 35 is directed to a non-transitory computer readable mediumcontaining instructions, wherein such instructions when executed by oneor more processors is configured to perform a method of performing userequipment (UE) autonomous selection in an evaluating UE. Such methodcomprises scheduling resources for discontinuous periodic transmissionhaving a scheduled discontinuous time period in which scheduledresources are not transmitted using one or more processors, performing amonitoring operation at the scheduled discontinuous time period, themonitoring operation comprising a monitoring for a collision ofscheduled resources of the evaluating UE with scheduled resources of acompeting UE using the one or more processors, and selectivelyperforming a corrective action when a collision of scheduled resourcesof the evaluating UE with scheduled resources of the competing UE isdetected during the monitoring operation using the one or moreprocessors.

Example 36 includes the subject matter of example 35, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises determining whether the evaluating UE will transmit on a nexttransmission time period based on a random selection having aprobability that the next transmission time period is a discontinuoustime period and thus not scheduled for data transmission on the nexttransmission time period.

Example 37 includes the subject matter of example 36, wherein theprobability is a preconfigured probability value.

Example 38 includes the subject matter of example 36, wherein theprobability depends upon a data priority associated with the scheduledresources.

Example 39 includes the subject matter of example 38, wherein theprobability is a high probability value greater than a nominalprobability value if the data priority is greater than predefinedthreshold.

Example 40 includes the subject matter of example 35, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises determining whether the evaluating UE will transmit on a nexttransmission time period based on a predefined periodicity of thescheduled discontinuous time period in which scheduled resources are nottransmitted.

Example 41 includes the subject matter of example 40, wherein thepredefined periodicity is randomly selected from a set of preconfiguredperiods.

Example 42 includes the subject matter of example 40, wherein thepredefined periodicity depends upon a data priority associated with thescheduled resources.

Example 43 includes the subject matter of example 35, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises determining that a next period will be a discontinuoustransmission period using the one or more processors, and setting aresource reservation period (RRP) field of a sidelink controlinformation (SCI) message of the evaluating UE to a new value thatdoubles a period of periodic transmission with respect to a previous RRPfield value of the evaluating UE using the one or more processors.

Example 44 includes the subject matter of example 35, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises determining that a next period will be a discontinuoustransmission period, and setting a bit in a sidelink control information(SCI) message field to a predetermined value that indicates that ascheduled resource in the next transmission period is not reserved fordata transmission, but the scheduled resource in a transmission periodfollowing the next transmission period is reserved for datatransmission.

Example 45 includes the subject matter of example 35, wherein whenperforming the monitoring operation at the scheduled discontinuous timeperiod, the method comprises evaluating one or more relevant frequencychannels for sidelink control information (SCI) messages of one or morecompeting UEs, and for each SCI message detected in the relevantfrequency channels, determining whether any scheduled resources of theone or more competing UEs collide with scheduled resources of theevaluating UE.

Example 46 includes the subject matter of example 35, wherein whenselectively performing the corrective action when a collision isdetected, the method comprises evaluating whether a resource reservationperiod (RRP) of a competing UE is identical to an RRP of the evaluatingRRP, and selectively stopping discontinuous periodic transmission by theevaluating UE on the scheduled resources and perform a re-selectionoperation to reschedule resources for discontinuous periodictransmission on different reserved resources.

Example 47 includes the subject matter of example 46, and furthercomprises determining whether a data priority of the evaluating UE isgreater than a data priority of the competing UE, and taking nocorrective action if the data priority of the evaluating UE is greaterthan the data priority of the competing UE.

Example 48 includes the subject matter of example 35, wherein whenselectively performing the corrective action when a collision isdetected, the method comprises evaluating whether a resource reservationperiod (RRP) of a competing UE is an integer multiple of the RRP of theevaluating UE, and selectively stopping periodic transmission on onlythose reserved resources by the evaluating UE that collide withtransmissions of the competing UE when the RRP of the competing UE is aninteger multiple of the RRP of the evaluating UE.

Example 49 includes the subject matter of example 48, and furthercomprises determining whether a data priority of the evaluating UE isgreater than a data priority of the competing UE, and taking nocorrective action if the data priority of the evaluating UE is greaterthan the data priority of the competing UE.

Example 50 includes the subject matter of example 35, wherein whenselectively performing the corrective action when a collision isdetected, the method further comprises evaluating whether a resourcereservation period (RRP) of the evaluating UE is an integer multiple ofthe RRP of the competing UE, and sending a message from the evaluatingUE to the competing UE to skip periodic transmission on scheduledresources that collide with the scheduled resources of the evaluating UEwhen the RRP of the evaluating UE is an integer multiple of the RRP ofthe competing UE.

Example 51 includes the subject matter of example 35, wherein whenselectively performing the corrective action when a collision isdetected, the method comprises evaluating whether a resource reservationperiod (RRP) of the evaluating UE is an integer multiple of the RRP ofthe competing UE, and stopping discontinuous periodic transmission andperform a re-selection operation to reschedule resources fordiscontinuous periodic transmission on different reserved resources.

The term “couple” is used throughout the specification. The term maycover connections, communications, or signal paths that enable afunctional relationship consistent with the description of the presentdisclosure. For example, if device A generates a signal to controldevice B to perform an action, in a first example device A is coupled todevice B, or in a second example device A is coupled to device B throughintervening component C if intervening component C does notsubstantially alter the functional relationship between device A anddevice B such that device B is controlled by device A via the controlsignal generated by device A.

It is well understood that the use of personally identifiableinformation should follow privacy policies and practices that aregenerally recognized as meeting or exceeding industry or governmentalrequirements for maintaining the privacy of users. In particular,personally identifiable information data should be managed and handledso as to minimize risks of unintentional or unauthorized access or use,and the nature of authorized use should be clearly indicated to users.

1. An evaluating user equipment (UE), comprising: memory; one or moreprocessors communicatively coupled to the memory and configured to:schedule resources for discontinuous periodic transmission having ascheduled discontinuous time period in which scheduled resources are nottransmitted; perform a monitoring operation at the scheduleddiscontinuous time period, the monitoring operation comprising amonitoring for a collision of scheduled resources of the evaluating UEwith scheduled resources of a competing UE; and selectively perform acorrective action when a collision of scheduled resources of theevaluating UE with scheduled resources of the competing UE is detectedduring the monitoring operation.
 2. The evaluating UE of claim 1,wherein when scheduling resources for discontinuous periodictransmission, the one or more processors are configured to: determinewhether the evaluating UE will transmit on a next transmission timeperiod based on a random selection having a probability that the nexttransmission time period is a discontinuous time period and thus notscheduled for data transmission on the next transmission time period. 3.The evaluating UE of claim 2, wherein the probability is a preconfiguredor configured probability value.
 4. The evaluating UE of claim 2,wherein the probability depends upon a data priority associated with thescheduled resources.
 5. The evaluating UE of claim 4, wherein theprobability is a high probability value greater than a nominalprobability value if the data priority is greater than a predefinedthreshold. 6-8. (canceled)
 9. The evaluating UE of claim 1, wherein whenscheduling resources for discontinuous periodic transmission, the one ormore processors are configured to: determine that a next period will bea discontinuous transmission period; and set a resource reservationperiod (RRP) field of a sidelink control information (SCI) message ofthe evaluating UE to a new value that doubles a period of periodictransmission with respect to a previous RRP field value of theevaluating UE.
 10. The evaluating UE of claim 1, wherein when schedulingresources for discontinuous periodic transmission, the one or moreprocessors are configured to: determine that a next period will be adiscontinuous transmission period; and set a bit in a sidelink controlinformation (SCI) message field to a predetermined value that indicatesthat a scheduled resource in the next transmission period is notreserved for data transmission, but the scheduled resource in atransmission period following the next transmission period is reservedfor data transmission. 11-13. (canceled)
 14. The evaluating UE of claim1, wherein when selectively performing the corrective action when acollision is detected, the one or more processors are configured to:evaluate whether a resource reservation period (RRP) of a competing UEis an integer multiple of the RRP of the evaluating UE; and selectivelystop periodic transmission on only those reserved resources by theevaluating UE that collide with transmissions of the competing UE whenthe RRP of the competing UE is an integer multiple of the RRP of theevaluating UE. 15-17. (canceled)
 18. A method of performing userequipment (UE) autonomous selection in an evaluating UE within avehicle-to-anything (V2X) communication environment, the methodcomprising: scheduling resources for discontinuous periodic transmissionhaving a scheduled discontinuous time period in which scheduledresources are not transmitted using one or more processors; performing amonitoring operation at the scheduled discontinuous time period, themonitoring operation comprising a monitoring for a collision ofscheduled resources of the evaluating UE with scheduled resources of acompeting UE using the one or more processors; and selectivelyperforming a corrective action when a collision of scheduled resourcesof the evaluating UE with scheduled resources of the competing UE isdetected during the monitoring operation using the one or moreprocessors. 19-22. (canceled)
 23. The method of claim 18, wherein whenscheduling resources for discontinuous periodic transmission, the methodcomprises: determining whether the evaluating UE will transmit on a nexttransmission time period based on a predefined periodicity of thescheduled discontinuous time period in which scheduled resources are nottransmitted.
 24. The method of claim 23, wherein the predefinedperiodicity is randomly selected from a set of preconfigured orconfigured periods.
 25. The method of claim 23, wherein the predefinedperiodicity depends upon a data priority associated with the scheduledresources. 26-28. (canceled)
 29. The method of claim 18, wherein whenselectively performing the corrective action when a collision isdetected, the method comprises: evaluating whether a resourcereservation period (RRP) of a competing UE is identical to an RRP of theevaluating RRP; and selectively stopping discontinuous periodictransmission by the evaluating UE on the scheduled resources and performa re-selection operation to reschedule resources for discontinuousperiodic transmission on different reserved resources.
 30. The method ofclaim 29, further comprising: determining whether a data priority of theevaluating UE is greater than a data priority of the competing UE; andtaking no corrective action if the data priority of the evaluating UE isgreater than the data priority of the competing UE. 31-34. (canceled)35. A non-transitory computer readable medium containing instructions,wherein such instructions when executed by one or more processors isconfigured to perform a method of performing user equipment (UE)autonomous selection in an evaluating UE, the method comprising:scheduling resources for discontinuous periodic transmission having ascheduled discontinuous time period in which scheduled resources are nottransmitted using the one or more processors; performing a monitoringoperation at the scheduled discontinuous time period, the monitoringoperation comprising a monitoring for a collision of scheduled resourcesof the evaluating UE with scheduled resources of a competing UE usingthe one or more processors; and selectively performing a correctiveaction when a collision of scheduled resources of the evaluating UE withscheduled resources of the competing UE is detected during themonitoring operation using the one or more processors. 36-44. (canceled)45. The non-transitory computer readable medium of claim 35, whereinwhen performing the monitoring operation at the scheduled discontinuoustime period, the method comprises: evaluating one or more relevantfrequency channels for sidelink control information (SCI) messages ofone or more competing UEs; and for each SCI message detected in therelevant frequency channels, determining whether any scheduled resourcesof the one or more competing UEs collide with scheduled resources of theevaluating UE. 46-47. (canceled)
 48. The non-transitory computerreadable medium of claim 35, wherein when selectively performing thecorrective action when a collision is detected, the method comprises:evaluating whether a resource reservation period (RRP) of a competing UEis an integer multiple of the RRP of the evaluating UE; and selectivelystopping periodic transmission on only those reserved resources by theevaluating UE that collide with transmissions of the competing UE whenthe RRP of the competing UE is an integer multiple of the RRP of theevaluating UE.
 49. The non-transitory computer readable medium of claim48, wherein the method comprises: determining whether a data priority ofthe evaluating UE is greater than a data priority of the competing UE;and taking no corrective action if the data priority of the evaluatingUE is greater than the data priority of the competing UE.
 50. Thenon-transitory computer readable medium of claim 35, wherein whenselectively performing the corrective action when a collision isdetected, the method further comprises: evaluating whether a resourcereservation period (RRP) of the evaluating UE is an integer multiple ofthe RRP of the competing UE; and sending a message from the evaluatingUE to the competing UE to skip periodic transmission on scheduledresources that collide with the scheduled resources of the evaluating UEwhen the RRP of the evaluating UE is an integer multiple of the RRP ofthe competing UE.
 51. The non-transitory computer readable medium ofclaim 35, wherein when selectively performing the corrective action whena collision is detected, the method comprises: evaluating whether aresource reservation period (RRP) of the evaluating UE is an integermultiple of the RRP of the competing UE; and stopping discontinuousperiodic transmission and perform a re-selection operation to rescheduleresources for discontinuous periodic transmission on different reservedresources.